Pesticides detected in Fanad East and Buncrana water supplies

28 May 2021

An exceedance for the pesticide Bentazone has been detected in the public drinking water supply in Fanad East (Shannagh) and for the pesticide MCPA in the public drinking water supply in Buncrana.

Bentazone is an active substance present in commercial herbicide products used to control broadleaf weeds in spring and winter field beans, broad bean, dwarf French bean, runner bean, dry beans, combining pea, vining pea, linseed, ornamental plant production, maize and potatoes. MCPA is an active substance present in many commonly used herbicide products used to control the growth of thistles, docks and rushes. These exceedances were detected as part of Irish Water’s public water supply monitoring programme.

The Fanad East (Shannagh) water supply abstracts raw water from the Shanagh Lake and Buncrana water supply abstracts water from Lough Doo, both of which are vulnerable to runoff from land. Irish Water is asking users of any herbicide or pesticide products in the Shanagh Lake and Lough Doo catchments to consider the vulnerability of the water supplies to pesticide contamination and the importance of this supply to the local homes and businesses in the community.

Irish Water, working in partnership with a range of organisations involved in the National Pesticides and Drinking Water Action Group (NPDWAG), is asking the farming community, greens keepers, grounds keepers, and domestic users, to consider in each case whether they need to use pesticides at all. Minimising pesticide use not only helps to protect water quality but also has wider environmental benefits. For example, leaving areas unsprayed can help native flowering plant species to grow and support a range of insects including bees and other vital pollinators. One third of Ireland’s bee species are threatened with extinction and by helping the bee population survive and thrive we are also helping to protect our precious water sources. For more information on practical ways to help bees and other pollinators, check out the All-Ireland Pollinator Plan.

Where pesticide use is considered necessary, the NPDWAG is working with the community to ensure that best practice measures to protect drinking water sources and biodiversity are always followed. Farmers and other landholders dealing with the challenge of tackling rushes should note that the Department of Agriculture, Food and the Marine (DAFM) has developed new guidance on the sustainable management of rushes. The new approach is based on the concepts of containment or suppression and aims to minimise the use of pesticides. More information on this can be obtained from your local farm advisor or on www.pcs.agriculture.gov.ie/sud/waterprotection.

The efforts to reduce the incidence and level of these detections are being coordinated by the NPDWAG. This group is chaired by the DAFM. All of the key stakeholders are represented in this group and include other Government departments and agencies; local authorities; industry representative bodies; farming organisations; water sector organisations; and amenity sector organisations. 

Dr Pat O’Sullivan, Irish Water’s Regional Drinking Water Compliance Specialist said: “In Co Donegal, we have a number of drinking water supplies impacted by pesticides including Ballymagroarty, Donegal (River Eske), Fanad East (Shannagh) and most recently Buncrana public water supplies following routine sampling. What’s disappointing is that this now means we have more than 10% of public drinking water supplies in Donegal impacted by pesticides in 2021. The most recent pesticide detections in Co Donegal were noted in the Fanad East (Shannagh) and Buncra public water supplies following routine sampling in May 2021. MCPA detections were previously detected in the Fanad East (Shannagh) in 2020. While our consultation with the HSE has concluded that the levels seen do not represent a threat to public health, it is however undesirable and therefore imperative that users of pesticides are mindful of best practice when using herbicides or pesticides and seek out alternatives.

Adding to this, Dr Aidan Moody, DAFM and Chair of NPDWAG commented: “The continued engagement of all stakeholders, working in partnership, is needed to tackle this issue. Users of pesticides should always consider alternatives in the first instance and if pesticides are essential make sure that they are aware of the best practice measures that should be followed to protect water quality.

Recent drinking water monitoring results for Ireland show that a number of active substances contained in herbicide products used in agriculture, amenity and gardens, such as 2,4-D, fluroxypyr, glyphosate, MCPA, mecoprop and triclopyr, are being regularly detected.

If pesticides have to be used, the basic steps to reduce risks to drinking water sources and the aquatic environment are:

  • Choose the right pesticide product (note that products containing MCPA are NOT approved for use in weed-wipers.)
  • Read and follow the product label
  • Determine the right amount to purchase and use
  • Don’t use pesticides if rain is forecast in the next 48 hours
  • Make sure you are aware of the location of all nearby water courses
  • Comply with any buffer zone specified on the product label to protect the aquatic environment. Mark out the specified buffer zone from the edge of the river or lake or other water course and drainage ditches
  • Avoid spills, stay well back from open drains and rinse empty containers 3 times into the sprayer.
  • Store and dispose of pesticides and their containers properly.
  • Never fill a sprayer directly from a water course or carry out mixing, loading or other handling operations beside a water course

Further guidance:

  • A video on the best practice use and application of products containing MCPA can be viewed on Irish Water’s YouTube channel.
  • Information leaflets on pesticide use are also available to download from the Teagasc website.

Tractor and sprayer in rushy field